The goal of this project is to dissect which mechanisms the B cell receptor (BCR) signaling network employs to govern life and death cellular functions in healthy B cells, determine how the BCR signaling network is remodeled in three types of cancer with abnormal BCR signaling, and then kill malignant B cells by identifying and targeting those mechanisms which are required for survival. A combination of technologies, including measurement of signaling in individual cells from primary human tissues by flow cytometry and computational modeling of the BCR signaling network, will be used to achieve this goal. Signal transduction plays a key role in the development of healthy immune cells, and remodeling of cell signaling mechanisms drives tumor cell proliferation and suppresses apoptosis, contributing to tumor survival despite intense therapy regimens. In B cell non-Hodgkin's lymphomas, signaling through the B cell antigen receptor might be especially likely to support malignant B cells, as BCR signaling normally controls survival, apoptosis, and proliferation throughout development and differentiation. The central hypothesis of this project is that abnormal BCR signaling is required for the survival of lymphoma B cells. I have previously shown that signaling in human cancer specimens can be mapped at the individual cell level by flow cytometry and used this technology to identify cancer-cell specific alteration of BCR signaling in primary human lymphoma specimens. Here, I propose to integrate this single cell signaling profile approach with measurements of the functional outcomes of signaling, including cell death, proliferation, and gene expression. The Specific Aims are to (I) identify BCR signaling mechanisms required for contrasting functions - apoptosis and proliferation - in five stages of healthy human B cells, (II) identify abnormal BCR signaling activity in three mature B cell lymphomas and determine unique signaling features of each disease, and (III) identify abnormal BCR signaling events that are required for survival of lymphoma B cells and target these events to specifically kill lymphoma cells. This project will advance cancer research by first clarifying our understanding of how signal transduction normally governs cell behavior and then by translating this mechanistic insight into a sharp understanding of critical 'targets of opportunity'in the signaling networks of malignant B cells. PUBLIC HEALTH RELEVANCE: Incidence and death rates from lymphoma in the United States are rising more rapidly than those of any other cancer except melanoma. The goal of my project is to improve the diagnosis and treatment of human cancer by dissecting the life and death signaling biology of lymphoma B cells. Signaling allows healthy cells to sense and respond to their environment, but cancer cells often ignore or misinterpret environmental signals in order to stay alive. I have chosen to focus on the central survival signaling pathway of B cells - B cell antigen receptor (BCR) signaling - because my research and that of others provides compelling evidence that this pathway is required for the survival of lymphoma B cells. During my Ph.D. research, I invented the central technology I will use in this project - the 'single cell signaling profile.'This technique enables the tracking and measurement of signaling within every single cell within a patient's lymphoma tumor sample. A key advantage of this approach is that I can examine the effect that a drug has on tumor-infiltrating immune cells and rare, aggressive subpopulations of cancer cells. Using this technology, I will (I) determine how BCR signaling governs healthy B cells and prevents them from unregulated proliferation, (II) identify unique BCR signaling events that distinguish three different B cell malignancies, both from each other and from healthy B cells, and (III) develop methods to target and destroy the malignant B cells by interrupting the BCR signaling events required for lymphoma cell survival. At the conclusion of this research, I will have used new knowledge of signaling to create tools which can profile an individual patient's cancer cells and identify key 'targets of opportunity'in the signaling network. I aim to found my own independent research group to develop the single cell signaling profiles into a rapid diagnostic tool that will eventually suggest personalized therapeutic strategies ideally suited to kill all of the cancer cells and as few healthy cells as possible. This award would significantly advance my long term career goal of using biological and computational tools to create personalized, effective therapies for human cancer.